Geophysical surveying (e.g., seismic, electromagnetic) is a technique where two- or three-dimensional “pictures” of the state of an underground formation are taken. Geophysical surveying takes place not only on land, but also in marine environments (e.g., ocean, large lakes). Marine geophysical survey systems use a plurality of sensor cables, which contain one or more sensors to detect acoustic energy emitted by one or more sources and returned from a hydrocarbon reservoir and/or associated subsurface formations beneath the sea floor. Sensor cables, in some embodiments may comprise sensor streamers which may be towed through a water body by a survey vessel, and in other embodiments ocean bottom cables disposed on the sea floor or entrenched within the seabed.
In embodiments deployed on the sea floor or entrenched in the seabed, which may be referred to as permanent reservoir monitoring (PRM) systems, there can be water exposure for relatively long periods of time (e.g., months or years). For example, PRM systems may be designed for decades of operation in ultra-deep water (e.g., greater than 1500 m), while also remaining suitable for use at shallower depths. In such subsea applications based on optically-powered sensors and optical telemetry, conventional wisdom for such applications dictates the use of gel-filled stainless steel conduits for the optical fibers with robust hermetic seals at every connection and each of the sensor splices, which typically number in the hundreds and possibly the thousands. Each seal represents a cost and a potential failure location. Thus, mechanisms to reduce the need for such seals and splice encapsulations would be advantageous.